This invention relates in general to a device for detecting and monitoring gas contaminated filter systems. More particularly, this invention concerns itself with a device which utilizes semiconducting polymers as a means for monitoring the degree of contamination of gas filters that are ultimately rendered useless as a gas filtering system due to the absorption of a contaminating gas on the filtering elements of the system. In a more specific aspect, the invention relates to a device for the continuous, real-time detection of chemical warfare agents, such as organophosphorous compounds, that are diffused through a charcoal filter and ultimately render it useless due to contamination.
The effect of pesticides and other chemical contaminants on the environment has generated considerable interest from an ecological standpoint. This interest has provided the impetus for a concentrated research effort in an attempt to develop monitoring systems for detecting the presence of contaminants in the environment. Because of the deadly and persistent effects produced by pesticides, and their structurally related chemical warfare counterparts, the development of simple, reliable and rugged detection systems, that are selective and sensitive to particular contaminants, has become a matter of vital importance to ecologically concerned groups as well as military strategists.
Many analytical methods have been developed for detecting chemical contaminants in water or soil. Gas chromatography, flame photometers and alkali-flame detectors are frequently employed. However, there are few methods and devices which monitor contaminants in the atmosphere.
With the present invention, however, there has been developed a device which meets the criteria of ruggedness, simplicity, reliability and sensitivity for detecting the organophosphorous compounds used as chemical warfare agents. The device is specifically useful in monitoring and detecting the degree of contamination which can occur in the charcoal filtering system used to filter out chemical warfare agents which may be contaminating a military environment such as the interior of trucks, tanks, aircraft, naval vessels and protective shelters.
The operating principle of this invention is based on measuring the bulk conductivity associated with semiconductive polymers that are specifically chemically reactive with organophosphorous chemical warfare compounds. The usefulness of the invention is found in the fact that a contaminant filtering unit replacement can be made based on the actual degree of contamination rather than on a somewhat haphazard and unreliable estimate of the potential operational life of the filtering unit.